Class D transits
Can anyone who controls Class D tell me whether they would normally prefer me to request an IFR or VFR transit clearance through their airspace (when flying in VMC)? I prefer to transit as high as possible to keep out of the way of slower traffic, e.g 5000ft through Solent and FL075 through the Channel Islands airspace. Most of the time you ask whether I would like an IFR or VFR clearance, obviously I don't want to risk the possibility of being denied entry if I choose the wrong option.